Angle sensor for a steerable boring tool

Claim 2

A sensor for determining an orientation of a member, said sensor comprising: a housing; a plurality of capacitors formed by electrodes arranged on opposed first and second walls of said housing to have a predetermined relationship to the orientation of said member; a fluid contained in said housing, said fluid present between electrodes of at least one capacitor and absent between electrodes of at least one other capacitor at orientations of said member; addressing means for individually addressing said capacitors in sequence; detecting means for detecting a presence or absence of fluid between the electrodes of each addressed capacitor and setting respective flags in accordance with the detected presence or absence of fluid; and determining means for determining the roll angle of said rotatable member in accordance with a sequence of said respective flags and the predetermined relationship of the capacitors to the orientation of said member.

Claim 3

The sensor according to claim 1 wherein said fluid comprises a non-conductive liquid.

Claim 4

The sensor according to claim 2 wherein said non-conductive liquid has a dielectric constant greater than the dielectric constant of air.

Claim 5

The sensor according to claim 1 wherein said fluid comprises a dielectric liquid.

Claim 6

The sensor according to claim 4 wherein said dielectric liquid has a dielectric constant greater than the dielectric constant of air.

Claim 7

The sensor according to claim 1 wherein said fluid comprises a conductive liquid.

Claim 8

The sensor according to claim 6 wherein said conductive liquid has a conductivity greater than the conductivity of air.

Claim 9

The sensor according to claim 1 wherein said fluid comprises a resistive liquid.

Claim 10

The sensor according to claim 8 wherein said resistive liquid has a resistivity greater than the resistivity of air.

Claim 11

The roll angle sensor according to claim 1 wherein said addressing means comprises: charging means for initially charging an addressed capacitor; and discharging means for discharging said charged capacitor.

Claim 12

The roll angle sensor according to claim 10 wherein said detecting means comprises: comparing means for comparing the charge on said discharging capacitor after a predetermined time period to a predetermined value; and means for setting a flag if the charge on said discharging capacitor is greater than the predetermined value due the presence of fluid between the electrodes thereof.

Claim 13

The roll angle sensor according to claim 1 wherein said addressing means comprises: discharging means for initially discharging an addressed capacitor; and charging means for charging said discharged capacitor.

Claim 14

The roll angle sensor according to claim 12 wherein said detecting means comprises: comparing means for comparing the charge on said charging capacitor after a predetermined time period to a predetermined value; and means for setting a flag if the charge on said charging capacitor is less than the predetermined value due the presence of fluid between the electrodes thereof.

Claim 15

The roll angle sensor according to claim 1 wherein said addressing means comprises: means for applying a high level signal to an addressed capacitor.

Claim 16

The roll angle sensor according to claim 14 wherein said detecting means comprises: circuit means for setting a flag when the charge transferred by said addressed capacitor is greater than a predetermined value.

Claim 17

The roll angle sensor according to claim 1 comprising sixteen capacitors.

Claim 18

The roll angle sensor according to claim 1 wherein said capacitors are defined by a circular array of electrodes on said first wall and a common electrode on said second wall.

Claim 19

The roll angle sensor according to claim 17 wherein said circular array of electrodes comprises sixteen electrodes.

Claim 20

The roll angle sensor according to claim 1 wherein said fluid comprises a conductive liquid selected from the group consisting of salt water, ethyl glycol, mercury, cupric nitrate, and methyl alcohol.

Claim 21

The sensor according to claim 1, wherein said housing is defined by a planar member and an electrically grounded cup-shaped member whose peripheral edges are crimped over an outer edge of said planar member and said plurality of capacitors is defined by a circular array of electrodes on an inner surface of said planar member and a common electrode formed by said cup-shaped member.

Claim 22

An underground boring tool comprising: a drill bit including a blade portion; a sensor for determining an orientation of said drill bit, said sensor comprising: a housing; a plurality of capacitors formed by electrodes arranged on opposed first and second walls of said housing to have a predetermined relationship to the orientation of said drill bit; a fluid contained in said housing and disposed between electrodes of at least one capacitor; addressing means for individually addressing each of said capacitors in sequence; detecting means for detecting a presence or absence of fluid between the electrodes of each addressed capacitor and setting respective flags in accordance with the detected presence or absence of fluid; and determining means for determining the orientation of said drill bit in accordance with a sequence of said respective flags and the predetermined relationship of the capacitors to the orientation of said drill bit; and a transmitter for transmitting a signal including the orientation of said drill bit.

Claim 23

An underground boring tool comprising: a drill bit including a blade portion; a sensor for determining an orientation of said drill bit, said sensor comprising: a housing; a plurality of capacitors formed by electrodes arranged on opposed first and second walls of said housing to have a predetermined relationship to the orientation of said drill bit; a fluid contained in said housing and disposed between electrodes of at least one capacitor; addressing means for individually addressing each of said capacitors in sequence; detecting means for detecting a presence or absence of fluid between the electrodes of each addressed capacitor and setting respective flags in accordance with the detected presence or absence of fluid; and determining means for determining the orientation of said drill bit in accordance with a sequence of said respective flags and the predetermined relationship of the capacitors to the orientation of said drill bit; and a transmitter for transmitting a signal including the orientation of said drill bit.

Claim 24

The underground boring tool according to claim 21 wherein said fluid comprises a dielectric liquid.

Claim 25

The underground boring tool according to claim 22 wherein said dielectric liquid has a dielectric constant greater than the dielectric constant of air.

Claim 26

The underground boring tool according to claim 21 wherein said fluid comprises a conductive liquid.

Claim 27

The underground boring tool according to claim 24 wherein said conductive liquid has a conductivity greater than the conductivity of air.

Claim 28

The underground boring tool according to claim 21 wherein said fluid comprises a resistive liquid.

Claim 29

The underground boring tool according to claim 26 wherein said resistive liquid has a resistivity greater than the resistivity of air.

Claim 30

The underground boring tool according to claim 21 wherein one of said first and second walls includes a dielectric coating.

Claim 31

The underground boring tool according to claim 28 wherein the dielectric coating comprises at least one layer of barium titanate.

Claim 32

The underground boring tool according to claim 29 wherein said dielectric coating further comprises a layer of glass disposed over said at least one layer of barium titanate.

Claim 33

The underground boring tool according to claim 21 wherein said fluid comprises methyl alcohol.

Claim 34

The underground boring tool according to claim 21 wherein said sensor comprises a roll angle sensor for determining a roll angle of said drill bit about a roll axis.

Claim 35

The underground boring tool according to claim 32 wherein said opposed first and second walls comprise opposed first and second planar walls which are substantially perpendicular to the roll axis.

Claim 36

The underground boring tool according to claim 21 wherein said sensor comprises a pitch sensor for determining a pitch of said drill bit about a horizontal axis.

Claim 37

The underground boring tool according to claim 34 wherein said opposed first and second walls comprise opposed first and second spaced planar surfaces which are substantially perpendicular to the horizontal axis.

Claim 38

The underground boring tool according to claim 35 wherein said pitch sensor determines a pitch within a range of ±45° about the horizontal axis.

Claim 39

The underground boring tool according to claim 21 wherein said addressing means comprises: charging means for initially charging an addressed capacitor; and discharging means for discharging said charged capacitor.

Claim 40

The underground boring tool according to claim 37 wherein said detecting means comprises: comparing means for comparing the charge on said discharging capacitor after a predetermined time period to a predetermined value; and means for setting a flag if the charge on said discharging capacitor is greater than the predetermined value due the presence of fluid between the electrodes thereof.

Claim 41

The underground boring tool according to claim 21 wherein said addressing means comprises: discharging means for initially discharging an addressed capacitor; and charging means for charging said discharged capacitor.

Claim 42

The underground boring tool according to claim 39 wherein said detecting means comprises: comparing means for comparing the charge on said charging capacitor after a predetermined time period to a predetermined value; and means for setting a flag if the charge on said charging capacitor is less than the predetermined value due the presence of fluid between the electrodes thereof.

Claim 45

A sensing device for determining an orientation of a member, said sensing device comprising at least two sensors, each sensor including a housing, a plurality of capacitors formed by electrodes arranged on opposed first and second walls of said housing to have a predetermined relationship to the orientation of said member, a fluid contained in said housing and disposed at least between electrodes of at least one capacitor, addressing means for individually addressing each of said capacitors in sequence, detecting means for detecting a presence or absence of fluid between the electrodes of each addressed capacitor and setting respective flags in accordance with the detected presence or absence of fluid, and determining means for determining the orientation of said member in accordance with a sequence of said respective flags and the predetermined relationship of said electrodes to the orientation of said member.

Claim 46

A sensing device for determining an orientation of a member, said sensing device comprising at least two sensors, each sensor including a housing, a plurality of capacitors formed by electrodes arranged on opposed first and second walls of said housing to have a predetermined relationship to the orientation of said member, a fluid contained in said housing and disposed at least between electrodes of at least one capacitor, addressing means for individually addressing each of said capacitors in sequence, detecting means for detecting a presence or absence of fluid between the electrodes of each addressed capacitor and setting respective flags in accordance with the detected presence or absence of fluid, and determining means for determining the orientation of said member in accordance with a sequence of said respective flags and the predetermined relationship of said electrodes to the orientation of said member.